Liste des documents
Caractérisation métallurgique et électrochimique d’une électrode ENiCrFe-3 avant et après fusion
L’objet de ce travail est de faire une étude comparative à travers une caractérisation métallurgique et électrochimique d’une électrode à base de nickel l’ENiCrFe-3 avant et après fusion lors d’un soudage manuel (SMAW). Plusieurs techniques de caractérisation ont été adoptées afin d’y parvenir à savoir : l’analyse EDX par Microscopie Electronique à balayage, des mesures de dureté HV10 ainsi que des essais électrochimiques. Voir les détails
Mots clés : Electrode ENiCrFe-3, enrobage rutile, microstructure, électrochimie, calamine
Comportement tribologique du composite à matrices métalliques (CMM) W-10Ni-5Fe élaboré par le procédé d’infiltration spontanée
Les composites à matrices métallique (CMM) pouvant combiner une dureté élevée et une ténacité convenable sont très recherchés dans des applications nécessitant une résistance à l’usure, à l’érosion et à la corrosion élevées. Ce travail s’intéresse particulièrement au comportement en frottements et usure à sec du CMM W-10Ni-5Fe contre une bille en céramique à base d’alumine (Al2O3) à température ambiante.La détermination du coefficient de frottement et du taux d'usure dans différentes conditions d’usure et l'analyse des morphologies des surfaces usées au MEB couplé à l’EDS ont permet de dégager l’effet des éléments nickel et fer sur la phase liante du composite. Le taux d'usure peut variait de 0,92 mm3(N.m)-1à 9 mm3(N.m)-1pour le composite W-10Ni-5Fe (% en poids). Les mécanismes d'usure des surfaces usées comportent les mécanismes d’usure d’adhésion et d’abrasion Voir les détails
Mots clés : Composite CMM, infiltration spontanée, comportement tribologie, frottement, usure
Effect of heat input variation on microstructure and mechanical behavior of SMAW welded super duplex joints
In the present study, the effect of heat input variation on microstructure and mechanical behavior of SAF 2507 super duplex stainless steel welded using 308L filler metal is investigated. A duplex austenitic-ferritic microstructure is observed in the weld metal whereas some ferrite grain growth is recorded in the heat affected zone (HAZ). Increasing heat input from 1.19 to 2.42 KJ/mm causes a decrease in ferrite amount in the WM and a slight grain growth in the HAZ. A change in the ferrite grain morphology from acicular to circular is also observed in the WM. A better combination of the mechanical properties and microstructual features is obtained for a heat input of 2.42 KJ/mm. Voir les détails
Mots clés : super duplex stainless steel, heat input, SMAW, alloying elements
The effect of successive repairs on the weldment quality of API 5L X-70 pipeline steel H.S.L.A
The effect of successive repairs on the weldment quality of API 5L X-70 pipeline steel H.S.L.A Voir les détails
Mots clés : welding, Heat affected zone, Thermal cycles, DRX, HSLA
Mechanical properties and characterization of metallic bond coat used in hardfacing of petroleum drill bits
Tungsten carbides are widely used as weld hardfacing deposits in petroleum drill bits. To assure proper bonding of the hardfacing to the substrate, several choices of bond coating layers are offered. In this study, tow different commercial powders A and B and mixtures of both them were thermal sprayed onto a carbon steel XC18 substrate used in petroleum drill bits. The micro hardness respectively, of the hardfacing surface and bond coating layers was measured. The microstructure was observed by optical microscopy and field emission scanning electron microscope equipped with energy-dispersive X-ray spectrometry. It has been observed that the mixture of 75% of A and 25% of B produces an uniform coating metallurgically bonded to the substrate with a little heat affected zone and a little amount of porosity. Voir les détails
Mots clés : Thermal spray coating, drill bit, Bond coat layer, weld hardfacing, adhesion.
Numerical Study of Thermal Effects in the Hydrodynamic Behavior of Textured Journal Bearings
The journals bearing characteristics with texture presence on the bearing surface are investigated. The thermal effect has been studied. The used numerical approach in this analysis is Finite Difference Method. The textured bearing performance enhancement passes essentially by a minimum film thickness and a friction torque improvement through an appropriate surface texture geometry and right texture distribution on the bearing surface. It is found that the simulation results are in good concordance with those issued from the litterature. The obtained results by considering the temperature effect are more realisti Voir les détails
Mots clés : Hydrodynamic lubrication, journal bearing, texturation, dimple
Microstructural and mechanical characterization of dissimilar weldedjoint between 2205 duplex stainless steel and API X52 HSLA steel
In this work we study the evolution of the microstructure and phase transformations along the welded joint and the mechanical properties of dissimilar metals weld between duplex stainless steel and HSLA steel. Welds are produced by shielded metal arc welding (SMAW) using a duplex grade filler metal (E2209). The welds obtained in this study, have good mechanical properties, despite the appearance of a hard zone at the interface between the weld metal and the heat affected zone of the HSLA steel Voir les détails
Mots clés : duplex stainless steel, API 5L X52, Dissimilar welding, Heat affected zone
Comparative analysis of surface texturing effect on the performance of hydrodynamic journal bearings
Understanding the influence of surface texturation on journal bearing performances inevitably involves experimental investigations pending being followed by a numerical modeling of the problem. This work consists to model and to understand the evolution of journal bearing characteristics with and without presence of textures on the bearing surface. The numerical approach based on the finite difference method is used in this analysis. Improving performance of textured bearing with spherical dimples suggest that contact characteristics such as minimum film thickness, maximum pressure, and friction torque may be improved through an appropriate surface texture geometry and appropriate texture distribution on the contact surface. The results of our simulations are in good agreement with those obtained experimentally [1]. Voir les détails
Mots clés : Journal bearings, Reynolds equation, Hydrodynamic lubrication, Stribeck curve, texture
The texture effect on the static characteristics of hydrodynamic journal bearings
Understanding the influence of surface texturationon journal bearing performances inevitably involvesexperimental investigations pending being followed by anumerical modeling of the problem. This work consists to modeland to understand the evolution of journal bearingcharacteristics with and without presence of textures on thebearing surface. The numerical approach based on the finitedifference method is used in this analysis. The results of oursimulations are in good agreement with those obtainedexperimentally by Xiaobin. Voir les détails
Mots clés : Cavitation, friction, hydrodynamics, Journal bearings, lubrication, numerical analysis, surface texture, Thin films, tribology
Microstructure and Mechanical Properties of a Dissimilar GTA Weld between 2205 duplex stainless steel and API X-70 high strength low alloy steel (HSLA)
The duplex stainless steels and HSLA steels are attractive for applications in the oil and gas industry due to their properties. The dissimilar welds are widely used in the petroleum industry for economical reason. However, the welding of dissimilar metals considered difficult, due to the differences in the physical properties of the two metals. The aim of the present study is to investigate the influence of the welding process parameters on the microstructure and mechanical properties of dissimilar weldement of 2205 duplex stainless steel /API X-70 high strength low alloy steel (HSLA) produced by GTA welding. The microstructures of the welded joints were investigated by the optical microscopy (OM), the mechanical properties included hardness, impact and tensile strength was investigated, the fracture surfaces of the tensile specimen were examined by scanning electron microscopy (SEM). From this investigation, it is observed that, the microstructural characteristics and mechanical proprieties of the weld are influenced by the heat input. Voir les détails
Mots clés : GTA welding, Dissimilar welding, heat input, duplex stainless steel, HSLA steel, microstructure, mechanical properties, Fractography